De novo myelodysplastic syndrome (MDS) with deletion of the long arm of chromosome 20: a subtype of MDS with distinct hematological and prognostic features?

Clonal hematopoiesis and acquired genetic abnormalities of the red cell: An historical review

Several syndromes affecting the red cell that mimic those induced by germline mutations may result from a somatic mutation that accompanies a myeloid malignancy. These syndromes are most notable in cases of myelodysplastic syndrome, but they are not limited to any one category of myeloid neoplasm. Their occurrence in males exceed the male predominance that is evident in myeloid neoplasms. The syndromes include disorders of globin chain synthesis (α- and β-thalassemia), heme synthesis (erythropoietic porphyria and erythropoietic uroporphyria), red cell membrane structure (elliptocytosis and spherocytosis), red cell enzyme activity (pyruvate kinase deficiency, glucose-6-phosphate dehydrogenase deficiency) and lowered expression of red cell ABO blood group antigens. This historical review describes the path to uncovering these acquired syndromes and their causal somatic mutations, where known. These syndromes often go unrecognized because of the dominant concern of the primary neoplasm. They may add to the healthcare needs of the patient.

Acquired elliptocytosis in chronic myeloid neoplasms: An enigmatic relationship to acquired red cell membrane protein and genetic abnormalities

Nineteen reports of 41 cases of acquired red cell elliptocytosis associated with a chronic myeloid neoplasm are described. Although the majority of cases have an abnormality of the long arm of chromosome 20, del(q20), several cases do not. Moreover, in one case a specific qualitative abnormality of red cell protein band 4.1(4.1R) was reported; however, several subsequent cases could find no abnormality of a red cell membrane protein or found a different abnormality, usually quantitative. Thus, this striking red cell phenotypic feature, acquired elliptocytosis, seen in myelodysplastic syndrome and other chronic myeloproliferative diseases, closely simulating the red cell phenotype of hereditary elliptocytosis, has an unexplained genetic basis, presumably as the result of an acquired mutation(s) in some chronic myeloid neoplasms.

Myelodysplastic Syndromes with Isolated 20q Deletion: A New Clinical-Biological Entity?

Aims: To define the peculiar features of patients with the deletion of the chromosome 20 long arm (del20q), data from 69 patients with myelodysplastic syndromes (MDSs) and isolated del20q, followed by the Gruppo Romano-Laziale Sindromi Mielodisplastiche (GROM-L) and Ospedale Torrette of Ancona, were collected and compared with those of 502 MDS patients with normal karyotype (NK-MDS). Results: Compared to the NK-MDS group, patients with del20q at diagnosis were older (p = 0.020) and mainly male (p = 0.006). They also had a higher rate of bone marrow blast < 5% (p = 0.004), a higher proportion of low and int-1 risk according to IPSS score (p = 0.023), and lower median platelet (PLT) count (p < 0.001). To date, in the del20q cohort, 21 patients (30.4%) received no treatment, 42 (61.0%) were treated with erythropoiesis-stimulating agents (ESA), 3 (4.3%) with hypomethylating agents, and 3 (4.3%) with other treatments. Among 34 patients evaluable for response to ESA, 21 (61.7%) achieved stable erythroid response according to IWG 2006 criteria and 13 (38.2%) were resistant. Nine patients (13.0%) progressed to acute myeloid leukaemia (AML) after a median time from diagnosis of 28 months (IR 4.1−51.7). The median overall survival (OS) of the entire cohort was 60.6 months (95% CI 54.7−66.4). the 5-year cumulative OS was 55.9% (95% CI 40.6−71.2). Conclusion: According to our results, we hypothesize that MDSs with isolated del 20q may represent a distinct biological entity, with peculiar clinical and prognostic features. The physio-pathological mechanisms underlying the deletion of the chromosome 20 long arm are still unclear and warrant future molecular analysis.

Reversal of isolated 20q deletion with vitamin B12 replacement in a patient with pernicious anaemia

Severe vitamin B₁₂ deficiency is well known to cause morphological alterations in bone marrow. In rare instances, these myelodysplastic and megaloblastic changes can coexist with cytogenetic abnormalities. Here, we report a case of a 38-year-old African-American woman with pernicious anaemia, who was found to have an isolated 20q deletion and which resolved after vitamin B₁₂ replacement. We also discuss various mechanisms in which vitamin B₁₂ deficiency can lead to chromosomal abnormalities. A literature review is also performed to evaluate various other chromosomal aberrations associated with B₁₂ deficiency.

Isolated deletion of the long arm of chromosome 20 [del(20q12)] in myelodysplastic syndrome: a case report and literature review

Isolated deletion of the long arm of chromosome 20 [del(20q12)] is a rare abnormality in patients with de novo myelodysplastic syndrome. It is characterised by refractory thrombocytopenia, minimal haematological dysplasia and a lower risk for progression to acute myeloid leukaemia. Its distinction from chronic autoimmune thrombocytopenia, although clinically and morphologically difficult, is critical. We report a case of refractory cytopenia and unilineage dysplasia in an elderly woman with isolated del(20q12), identified via fluorescence in situ hybridisation analysis of her bone marrow. In order to avoid a misdiagnosis, we suggest that cytogenetic analysis be performed on all patients suspected to have myelodysplastic syndrome with predominant thrombocytopenic presentation.

Morphology, cytogenetics, and survival in myelodysplasia with del(20q) or ider(20q): a multicenter study

Isochromosome of the long arm of chromosome 20 with interstitial loss of material [ider(20q)] is a rare cytogenetic abnormality reported in myelodysplastic syndrome (MDS), with neither specific morphological pattern nor clear prognostic significance. The aim of this retrospective multicentric study is to compare the peripheral blood and bone marrow morphology of MDS patients with ider(20q) (n = 13) and del(20q) (n = 21) and controls (n = 47) in order to investigate whether the ider(20q) harbors specific morphological features. The secondary objective is to compare the outcome of patients from both groups. This study performed on the largest cohort of MDS patients with ider(20q) is the first that identifies specific morphological features (hypogranulated and vacuolized neutrophils and neutrophil erythrophagocytosis) allowing the identification of this cytogenetic abnormality with high sensitivity (70%) and specificity (85.7%). Suspected ider(20q) by morphology should therefore support targeted FISH tests in case of non informative karyotype. This combined approach will allow a better estimation of the prevalence of this underdiagnozed entity. The overall survival and progression-free survival did not statistically differ in both groups. However, hypogranulated and vacuolized neutrophils were significantly associated with survival.

Current Treatment Options: Impact of Cytogenetics on the Course of Myelodysplasia

The heterogeneity of myelodysplastic syndromes (MDS) has driven the search for unifying biologic and clinical features that would stratify patients into distinct prognostic and therapeutic subgroups. Cytogenetics has been shown to impact the course of myelodysplasia. Despite the presence of non-random cytogenetic abnormalities in approximately 50% of MDS patients, it is significant that only a proportion of metaphases may contain the abnormality. Clonality studies however show that the karyotypically normal metaphases are still part of the MDS clone. This would suggest that the chromosomal abnormality may not be the initiating lesion in MDS, and that the gross karyotypic changes represent clonal evolution in a genetically unstable population. Yet, as will be described below, specific cytogenetic abnormalities are associated with clinically and biologically distinct forms of the disease, most notable in the response of del(5q) patients to lenalidomide. One possible explanation for the appearance of non-random mutational events could relate to the interaction of MDS cells with their microenvironment. Whatever the initiating lesion in the MDS stem cell, the end result is a clonal expansion where the marrow becomes populated by the monoclonal progeny of this cell. Interaction of these cells with a microenvironment which has been shown to be rich in pro-apoptotic cytokines such as tumor necrosis factor alpha (TNFa), leads to increased genetic instability. Hypoxia mediated decrease in DNA repair enzymes could further accelerate mutational events culminating in accumulation of multiple chromosomal abnormalities. Some of these chromosomal changes are associated with increased sensitivity to specific drugs. Lenalidomide has shown a high degree of efficacy in MDS patients with del(5q), although the target for the drug is unknown since a small but significant subset of MDS patients without del(5q) abnormality also respond to the drug. In contrast, the molecular target for imatinib mesylate is known; mutations in tyrosine kinase receptor family of genes found in patients with t(5;12) and del(4q12) make these individuals sensitive to the drug. Patients with isolated trisomy 8 have an immune component to the disease phenotype which can be targeted by cyclosporine and or anti-thymocyte globulin (ATG), especially in the presence of a PNH (paroxysmal nocturnal hemoglobinurea) clone. In the absence of these specific cytogenetic abnormalities described above, the two FDA approved hypomethylating agents 5 azacytidine and decitabine should be considered as therapeutic alternatives.

Prognostic diversity among cytogenetic abnormalities in myelofibrosis with myeloid metaplasia

BACKGROUND

Approximately 30-50% of patients with myelofibrosis with myeloid metaplasia (MMM) demonstrate detectable cytogenetic abnormalities, the prognostic value of which has not been completely defined by previous retrospective studies. The current prospective study addresses this issue in the context of currently accepted independent prognostic variables.

METHODS

The current study is a single institution study in which patients with MMM were accrued between January 2000 and August 2001 and followed in a prospective fashion. All study patients underwent bone marrow examination with cytogenetic studies as well as comprehensive clinical and laboratory evaluation at the time of karyotype analysis.

RESULTS

Among the study cohort of 81 patients (with a median age of 61 years; 54 males), the cytogenetic findings were normal in 44 patients (54%; Group 1). The remaining 37 patients (46%) demonstrated either interstitial deletions involving the long arm of chromosome 13 or 20 (9 patients; Group 2) or other abnormalities (28 patients; Group 3). All study patients were followed prospectively for a minimum of 40 months (range, 40-55 months). Survival from the time of karyotypic analysis was found to be similar between Groups 1 and 2 but was significantly worse in Group 3. Furthermore, none of the patients in Group 2 experienced leukemic transformation, whereas five patients each from the other two groups did. Multivariate analysis identified an unfavorable cytogenetic profile (Group 3), > or = 1% circulating blasts, a hemoglobin level of <10 g/dL, and constitutional symptoms as adverse prognostic features for overall survival.

CONCLUSIONS

Specific cytogenetic lesions in patients with MMM might carry an independent prognostic effect for both survival and the risk of leukemic transformation. Such information should assist in decision making when considering aggressive treatment approaches.

FISH studies identify the i(20q−) anomaly as a der(20)del(20)(q11q13)idic(20)(p11)

Fluorescence in situ hybridization (FISH) analyses were performed on six of seven patients who had been reported in 2004 to have an i(20q-) anomaly expressed as ider(20)(q10)del(20)(q11q13). The i(20q-) was investigated with a series of probes: a centromere-specific probe for chromosome 20, two paint probes for 20p and 20q, and a panel of locus-specific probes prepared from BAC/PAC clones mapped to 20p. The results showed that: (1) i(20q-) was a dicentric chromosome; (2) both of its arms comprised a deleted 20q and a small part of 20p near the centromere of chromosome 20; and (3) the breakpoints and reunion sites of i(20q-) differed, residing in the region 20p11.21-20p11.22 delineated by BAC/PAC clones RP11-96L6 and RP13-401N8. Thus, i(20q-) could be more precisely described as a der(20)del(20)(q11q13)idic(20)(p11).

The Human Orthologue of a Novel Apoptosis Response Gene Induced During Rat Myelomonocytic Stem Cell Apoptosis Maps to 20q13.12

Stem cell factor (SCF) stimulation of the receptor tyrosine kinase c-kit has effects on the proliferation, differentiation, and apoptotic regulation of hematopoietic progenitor cell populations. Rat bone marrow myelomonocytic stem cells (MSC) isolated in vitro by wheat germ agglutinin culture exclusively undergo self-renewal divisions when stimulated by SCF but bipotentially differentiate in the presence of dexamethasone or 1alpha,25-dihydroxyvitamin D(3) to granulocytes and macrophages, respectively. We show here that withdrawal of SCF from MSC induces rapid apoptosis in all stages of the cell cycle accompanied by development of an ultrastructural apoptotic morphology. To investigate immediate-early gene induction during MSC apoptosis, a differential display polymerase chain reaction (DD-PCR) screen coupled with rapid amplification of cDNA ends (RACE) PCR was performed. An immediate-early apoptosis response gene was isolated from growth factor-deprived MSC that was not expressed during self-renewal or differentiation induction cultures containing SCF. The protein contains a PEST region enriched in proline, glutamic acid, serine, and threonine residues common to proteins with a high turnover and has a cytoplasmic, vesicular localization in apoptotic MSC shown by immunohistochemistry. The human orthologous gene, isolated by RACE PCR, shows 86% homology to the rat protein and high similarity with a human uncharacterized hypothalamus predicted protein (HSMNP1) localized to the long arm of chromosome 20. Because deletions in this region are a common occurrence in a wide range of myeloproliferative disorders characterized by treatment resistance to apoptosis, HSMNP1 expression may play a role in normal and pathological myeloid development.

Isochromosome of a deleted 20q: a rare but recurrent chromosome abnormality in myelodysplastic syndromes

Interstitial deletion of the long arm of chromosome 20, as the sole abnormality, is commonly observed in myeloid malignancies, including myeloproliferative disorder, myelodysplastic syndrome, and acute myeloid leukemia. The breakpoints of the deletion are typically located in the region 20q11.2 approximately q13.3, although smaller deletions within this region have also been reported. We present here 4 patients with myelodysplastic syndrome with an isochromosome of the deleted long arm of chromosome 20: ider(20)(q10)del(20)(q11q13). Fluorescence in situ hybridization studies were performed on the bone marrow samples from these patients to prove the identity of this unusual chromosome abnormality.

Is fluorescence in situ hybridization a useful method in diagnosis of polycythemia vera patients?

Polycythemia vera (PV) is a clonal stem cell disease with trilineage myeloid involvement, characterized by a growth factor-independent erythroid proliferation. At the time of diagnosis, the percentage of cytogenetic abnormalities using conventional cytogenetic techniques is less than 20% of all PV patients. In the present study, we compare the results between conventional cytogenetic methods and fluorescence in situ hybridization (FISH) probes in 31 untreated PV patients. The karyotypes of all 31 cases were obtained from 24-hour bone marrow cell cultures. The fixed material, proceeding from conventional cytogenetics cultures, was analyzed with FISH, using centromeric probes for chromosomes 8 and 9 and locus-specific probes for 13q14 and 20q12 regions. Five cases (17.8%) showed an abnormal karyotype with conventional cytogenetics. When FISH probes were used, three alterations not detected with conventional cytogenetics, were found: two cases with D20S108 deletions and one with a D13S319 deletion, increasing the percentage of abnormal karyotypes to 19.3%. We conclude that, probably, the application of FISH with the mentioned probes, is not very useful to detect cytogenetic aberrations in untreated PV patients.

Clinical and molecular cytogenetic studies in seven patients with myeloid diseases characterized by i(20q−)

We report on seven patients with myeloid diseases characterized by i(20q-) anomaly. Four patients were male and three were female, their median age was 57 years. The diagnosis at presentation was myelodysplastic syndrome in six patients, acute myeloid leukaemia in one patient. Four died but three survived and remain anaemic. The survivals were 6 months for patient 1, 7 months for patient 2, 17 d for patient 4 and 28 d for patient 5. Chromosome specimens were prepared by direct and/or short-term culture of bone marrow cells. Karyotype analysis was performed by R- and G-banding technique, which showed that one of the normal chromosomes 20 was substituted by one or two small metacentric chromosomes in all seven patients. The karyotype was ider(20)(q10)del(20)(q11q13), i.e. i(20q-) in six patients by dual-colour fluorescence in situ hybridization assay using two probes (a subtelomeric probe for 20q and an unique probe for 20q12). As far as we know, this anomaly has not been reported previously. Thus, we consider that i(20q-) is a novel and rare recurrent chromosomal abnormality that is specifically associated with myeloid diseases and may indicate a poor prognosis.

Protein 4.1 deficiency and deletion of chromosome 20q are associated with acquired elliptocytosis in myelodysplastic syndrome

We report a case of myelodysplastic syndrome (MDS), associated with prominent elliptocytosis. A 66-year-old male presented with peripheral pancytopenia, and was diagnosed with MDS [refractory anaemia (RA)]. Apart from marked elliptocytosis, dyshaematopoietic features were not evident in his peripheral blood or hypercellular bone marrow. After 18 months, he had progressed to RA with excess blasts in transformation. Analysis of red blood cell membrane proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a reduced quantity of protein 4.1 (30% of control). Deletion of chromosome 20q was identified by conventional cytogenetic analysis and fluorescence in situ hybridization. Marked elliptocytosis, persistent for more than 17 months, decreased strikingly after chemotherapy with idarubicin and Ara-C. These findings suggest that acquired elliptocytosis occurred as an unusual morphological feature of MDS, associated with abnormalities of protein 4.1 and chromosome 20q.

[Biologic and clinical relevance of cytogenetic analysis in primary myelodysplastic syndromes]

Cytogenetic abnormalities in myelodysplastic syndromes (MDS) are complex and heterogeneous. The most frequent rearrangements (gains or losses of genetic material) vary from patient to patient, and within the same patient. The prognostic value of these rearrangements has been extensively studied. They allowed the definition of a risk based classification system for MDS (the International Scoring System for evaluating Prognosis, IPSS), proven to be a highly useful method for evaluating prognosis in MDS patients. Despite recent progress in mapping and definition of minimally deleted chromosomal regions, the primary critical genetic events remain to be determined. The recurrent cytogenetic abnormalities associated with MDS are likely to be secondary events contributing to but not initiating the neoplastic phenotype of the disease.

A new nonrandom unbalanced t(17;20) in myeloid malignancies

Deletions of chromosomes 17 and 20 are well-described abnormalities in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) but translocations involving these two chromosomes are uncommon. We present five male patients, one with MDS and four with AML, in whom a new, nonrandom unbalanced dicentric t(17;20), resulting in deletions of 17p and 20q, was identified. Conventional cytogenetics showed additional karyotypic abnormalities in most of the patients, including deletions of 5q, deletions or monosomy of chromosome 7, and deletions of 18q. Fluorescence in situ hybridization showed a deletion of the tumor suppressor gene TP53 on 17p. Of the four cases with follow-up data available, only two had received combination chemotherapy. Overall survival in these two cases was 6 and 7 weeks, respectively. Two other patients who had no active therapy administered died 6 weeks and 9 months after diagnosis, respectively. These five cases highlight a rare but recurrent abnormality in MDS and AML, potentially involving genes on 17p and 20q of importance in myeloid leukemogenesis.

The cytogenetics of myelodysplastic syndromes

The myelodysplastic syndromes are a collection of five clinico-pathological entities with a wide spectrum of clinical behaviours and survival outcomes. Cytogenetic analysis has been instrumental in refining the prognosis, predicting the likelihood of progression to acute myeloid leukaemia and median survival, and in establishing clonality of these diseases. This review highlights the most frequent abnormalities and summarizes their clinical and genetic features.

Myeloproliferative disorders

The myeloproliferative disorders (MPDs) are a group of pre-leukaemic disorders characterized by proliferation of one or more lineages of the myelo-erythroid series. Unlike the Philadelphia chromosome in chronic myeloid leukaemia, there is no pathognomonic chromosomal abnormality associated with the MPDs. Chromosomal abnormalities are seen in 30-40% of patients with polycythaemia vera (PV) and idiopathic myelofibrosis (IMF) and seem to indicate a poor prognosis. On the other hand, chromosomal abnormalities are rare in essential thrombocythaemia. Consistent acquired changes seen at diagnosis include deletion of the long arm of chromosome 20, del(13q), trisomy 8 and 9 and duplication of parts of 1q. Furthermore del(20q), trisomy 8 and dupl(lq) all arise in multipotent progenitor cells. Molecular mapping of 20q deletions and, to some extent, 13q deletions has identified a number of candidate target genes, although no mutations have yet been found. Finally, translocations associated with the rare 8p11 myeloproliferative syndrome and other atypical myeloproliferative disorders have permitted the identification of a number of novel fusion proteins involving fibroblast growth factor receptor-1.

Secondary acute myelogenous leukemia and myelodysplasia without abnormalities of chromosome 11q23 following treatment of acute leukemia with topoisomerase II-based chemotherapy

Therapy-related MDS and AML are complications of intensive chemotherapy regimens. Traditionally, patients exposed to topoisomerase II inhibitors are reported to develop secondary AML with abnormalities of chromosome 11q23. We evaluated the long-term hematologic toxicity of topoisomerase II-intensive high-dose mitoxantrone-based chemotherapy in 163 newly diagnosed acute leukemia patients treated over an 8 year period. Nine (5.5%) patients developed new cytogenetic abnormalities. Four patients developed MDS with progression to AML, three patients developed new abnormalities at the time of relapse, and three patients (including one of the former patients) had changes that were not associated with hematologic disease. The abnormalities most frequently involved chromosomes 7q, 20q, 1q, and 13q. Despite the use of topoisomerase II-intensive treatment, no patient developed an abnormality involving chromosome 11q23. Spontaneous resolution of some changes and prolonged persistence of others in the absence of hematologic disease indicates that some cytogenetic changes are not sufficient to promote leukemogenesis.

Chromosomal alterations associated with evolution from myelodysplastic syndrome to acute myeloid leukemia

Several studies have demonstrated the prognostic value of cytogenetic analysis in MDS both for survival and progression to AML. However it is unknown which are the numerical or structural abnormalities required for leukemic transformation. In this report we studied clinically and cytogenetically 127 patients: 125 with primary MDS and two with AML with a previous history of MDS. Thirty-one patients (24%) showed evolution of the disease during the follow-up study. Chromosomal abnormalities found at diagnosis in patients that progressed toward AML included: del(5)(q15), +6, del(6)(q21), t(5;8)(q32;q22),-7, del(7)(q22), der(7)t(1;7)(q10;p10), t(7;11)(p15;p15), +8, del(11)(q23), del(12p), del(3)(q21), del(20)(q12) and complex karyotypes. Eight of these patients were studied cytogenetically during transformation and showed acquisition of chromosomal alterations involving dup(1q), +8, del(11)(q23), and translocations between chromosomes 1 and 8 or 7 and 17. In addition we also observed gain of ploidy and monosomy 21. These results suggest that chromosomal alterations during evolution of the disease include special chromosome gains or abnormalities of chromosomes 1, 7, 8, 11 and 17 with involvement of ETV-1, Hox-A9, Pax 4, MLL genes besides a putative gene mapped at 17q25. We also applied the International Prognostic Scoring System (IPSS) to 114 patients, excluding those submitted to allogeneic bone marrow transplant. Our patients were classified into four distinct risk groups. The analysis of risk groups presented by 27 patients who showed evolution of the disease revealed 18 at the high risk group and four at the intermediate-2 group. From the intermediate-1 risk group only five patients showed evolution of the disease. Three of these patients evolved from RA to RAEB with gain of a del(11)(q23) or an expansion of a del(12)(p12) clone. Our results suggest that some chromosomal alterations are responsible for each step in the evolution of the disease. As the pathway of evolution is not unique it has been very difficult to define what genetic alteration comes first. However from several results in the literature and our own, it seems that some chromosomal alterations may predict the evolution of the disease and are correlated with short survival, as for example the trisomy of chromosome 8, and might be incorporated in the high risk group in the IPSS. This score system has been proved to be useful for predicting survival and evolution from MDS to AML.

Refinement of the smallest commonly deleted segment of chromosome 20 in malignant myeloid diseases and development of a PAC-based physical and transcription map

A deletion of the long arm of chromosome 20, del(20q), is a recurring abnormality in malignant myeloid diseases. In previous studies, we delineated a commonly deleted segment (CDS) of 5 Mb within band 20q12 flanked by D20S206 (proximal) and D20S481 (distal). We have generated a detailed physical map of P1 artificial chromosome (PAC) clones of this interval as well as a transcriptional map. The contig consists of 81 clones to which 152 markers (27 genes, 45 unique expressed sequence tags (ESTs) or UniGenes, 24 polymorphisms, and 56 sequence-tagged sites) have been mapped. Using PAC clones for fluorescence in situ hybridization analysis of myeloid leukemia cells with reciprocal translocations of 20q, or unbalanced rearrangements leading to loss of 20q, we have narrowed the CDS to an approximately 250-kb interval encompassing two overlapping PACs, P201E16 and P29M7 (between EST AA368224 and D20S481). This interval is gene-rich and contains 5 characterized genes, 4 UniGenes, and 9 single ESTs. The development of a transcriptional map and the identification of the smallest CDS will facilitate the molecular cloning of a myeloid leukemia suppressor gene on 20q.

Clinical analysis and TPO levels in three patients with refractory thrombocytopenia

Refractory thrombocytopenia (RTC) is a counter-concept to refractory anemia, which is characterized by isolated thrombocytopenia associated with clonal chromosomal abnormality. The diagnosis of RTC is difficult to establish based on morphologic features alone. And steroid therapy for RTC is often ineffective. We examined 3 patients with RTC to identify its characteristics and measured serum thrombopoietin levels. The mean platelet count was 5.1 x 10(4)/microl and the mean age was 64 years. None of our patients had clinical nor laboratory evidence of liver dysfunction, renal disease or disseminated intravascular coagulation. All patients were negative for antiplatelet antibody, PA-IgG and anticardiolipin-beta2GPI antibody. Leukocyte alkaline phosphatase level was low in two patients. Clonal chromosomal abnormalities of different types were detected in all patients. Bone marrow smears showed micromegakaryocytes. But there were no apparent morphological abnormalities of erythroid and granuloid series. Thrombopoietin levels, as determined by enzyme-linked immunosorbent assay, varied from <0.2 to 1.40 fmol/ml. We could not find the screening tool of RTC. In conclusion, there is a need to identify RTC from isolated thrombocytopenia because the patients with RTC don't have good prognosis as patients with isolated thrombocytopenia. Cytogenetic analysis is necessary to establish the diagnosis of RTC. We recommend that a patient above 50 years of age presenting with isolated thrombocytopenia and a low leukocyte alkaline phosphatase score should be suspected of having RTC.

Identification of multiple copies of a 20q-chromosome in a case of myelodysplastic syndrome: a FISH study

In myelodysplastic syndromes (MDS) karyotypic aberrations identify subgroups of patients with distinct clinical-morphological features and can be relevant in risk assessment of developing leukemia. Often conventional cytogenetic analysis is not sufficiently informative due to the presence of partially or completely unrecognizable chromosome markers. By chromosome microdissection (MD) and fluorescence in situ hybridization (FISH) we investigated the nature of a karyotypic marker occurring in multiple copies in one case of MDS arisen in a patient previously treated for breast cancer. Results showed dicentrics derived from telomeric fusion between interstitially deleted 20q-chromosomes. The abnormal karyotype resulted into polysomy for a deleted chromosome 20q.

Specific cutaneous lesions of the scalp in myelodysplastic syndrome with deletion of 20q

We reported a specific skin lesion on the scalp in a patient with myelodysplastic syndrome (MDS), treated as refractory anemia with excess of blasts (RAEB). Histologically, a specimen from a nodule of the scalp consisted of a diffuse infiltration of atypical cells in the dermis and subcutaneous tissue. The patient died of acute leukemia 3 months later. Chromosomal examination of bone marrow cells revealed deletion of 20q and 21 trisomy. The specific cutaneous lesions in this patient were associated with acute transformation. The deletion of 20q and specific cutaneous lesions are regarded as signs of poor prognosis.

Elliptocytosis in myelodysplastic syndrome associated with translocation (1;5)(p10;q10) and deletion of 20q

Acquired elliptocytosis is a red blood cell abnormality occasionally associated with myelodysplastic syndrome (MDS). A Japanese male with MDS who presented with elliptocytosis had mild anemia and hypercellular bone marrow with three lineage-dysplasia. He was diagnosed with refractory anemia of MDS. Cytogenetic analysis of bone marrow cells showed 47,XY,+1,der(1;5)(q10;p10),t(1;5) (p10;q10),del(20)(q11) in 70% of the analyzed cells. Analysis of red blood cell membrane proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed normal electrophoretic patterns with no quantitative abnormalities of each protein. Del(20q) and/or t(1;5)(p10;q10) might be associated with elliptocytosis in this patient.

Molecular genetics and cytogenetics of myeloproliferative disorders

The myeloproliferative disorders are believed to represent clonal malignancies resulting from transformation of a pluripotent stem cell. X-inactivation patterns of peripheral blood cells have been proposed as a useful diagnostic tool but this method is limited by the finding of a clonal X-inactivation pattern in a significant proportion of normal elderly women. There is no pathognomonic chromosomal abnormality associated with the myeloproliferative disorders. However, consistent acquired cytogenetic changes include del(20q), del(13q), trisomy 8 and 9 and duplication of segments of 1q, all of which have been observed at diagnosis or before cytoreductive therapy and therefore represent early lesions which contribute to the pathogenesis of these disorders. Although, the acquired molecular defects underlying most myeloproliferative disorders have not yet been elucidated, translocations associated with the rare 8p11 syndrome have permitted identification of a novel fusion protein. The role of a number of candidate genes in the other myeloproliferative disorders has also been studied, but no mutations have been identified so far. It is likely that a number of genes will be involved, given the varied phenotypes of the diseases. Identification of causal genes will be of considerable interest to both clinicians, who currently lack a specific and sensitive diagnostic test, and scientists interested in fundamental issues of stem cell behaviour.

Exposure to myelotoxic agents and myelodysplasia: case-control study and correlation with clinicobiological findings

To better define the role of exposure to myelotoxic agents in the genesis of myelodysplastic syndrome (MDS), we carried out (a) a case-control study for the determination of the relative risk (RR) of developing MDS, including 178 consecutive patients and 178 sex- and age-matched controls: (b) a study of clinicobiological features in MDS arising after occupational exposure to myelotoxic agents and in MDS in 'non-exposed' patients. The definition of the 'exposure' status was based on a predetermined questionnaire, with calculation of an 'exposure' index (hours/day x days/year x years). Cumulative exposure to pesticides or to organic solvents, for >2400 h, was recorded in 48 and 25 MDS patients, respectively, compared to 27 and four controls (P<0.00001; RR 3.74; 95% confidence interval 2.02-5.37). Older age and an excess of refractory anaemia with ringed sideroblasts and refractory anaemia with excess of blasts was noted among 'exposed' MDS-patients (group 1), compared to non-exposed MDS-patients (group 2). 68.3% patients in group 1 had clonal chromosome changes, compared with 43.2% patients in group 2. Complex karyotypes, -7/7q-, -5/5q-, +8, 7p and 17p aberrations were seen more frequently in group 1, whereas a normal karyotype, isolated 5q- or 20q- occurred more frequently in group 2. The association of exposure to myelotoxic agents with older age at presentation and with unfavourable chromosome changes accounted for the shorter survival observed in 'exposed' patients. These data show that occupational exposure to pesticides and organic solvents in our region resulted in an increased RR of developing MDS and that a distinct cytogenetic profile was associated with MDS in 'exposed' patients. These findings provide strong indirect evidence that these agents may play a role in the pathogenesis of MDS, preferentially targeting some of the chromosome regions which are frequently involved in therapy-related myeloid neoplasias.

Risk factors and their relationship to prognosis in myelodysplastic syndromes

Recent efforts have been directed at improving the methodology for predicting clinical outcomes in patients with myelodysplastic syndromes (MDS). This review focuses on the development of a consensual, prognostic, risk-based analysis system generated by the International MDS Risk Analysis Workshop. In the workshop, cytogenetic, morphological, and clinical data were combined and collated from a relatively large group of patients with primary MDS. Critical prognostic variables were evaluated using the data set. Based on these findings, the International Prognostic Scoring System (IPSS) was developed, compared with other systems, and shown to provide more accurate prognoses regarding survival and evolution to acute myeloid leukemia in MDS patients. The improvement was due to several features of the workshop model: more refined cytogenetic categorization, inclusion of cytopenias, improved subdivision of marrow blast percentages, four subgroups defining outcome, and separate stratification for age. The IPSS should result in better-defined clinical outcomes in MDS and provide a framework for future studies determining the possible role of molecular determinants (e.g. oncogenes, tumor suppressor genes, cytokine expression and responsiveness) for evaluating prognoses. The IPSS will likely prove useful in the design and analysis of therapeutic trials in MDS as well as in patient management.

International Scoring System for Evaluating Prognosis in Myelodysplastic Syndromes

Despite multiple disparate prognostic risk analysis systems for evaluating clinical outcome for patients with myelodysplastic syndrome (MDS), imprecision persists with such analyses. To attempt to improve on these systems, an International MDS Risk Analysis Workshop combined cytogenetic, morphological, and clinical data from seven large previously reported risk-based studies that had generated prognostic systems. A global analysis was performed on these patients, and critical prognostic variables were re-evaluated to generate a consensus prognostic system, particularly using a more refined bone marrow (BM) cytogenetic classification. Univariate analysis indicated that the major variables having an impact on disease outcome for evolution to acute myeloid leukemia were cytogenetic abnormalities, percentage of BM myeloblasts, and number of cytopenias; for survival, in addition to the above, variables also included age and gender. Cytogenetic subgroups of outcome were as follows: “good” outcomes were normal, −Y alone, del(5q) alone, del(20q) alone; “poor” outcomes were complex (ie, ≥3 abnormalities) or chromosome 7 anomalies; and “intermediate” outcomes were other abnormalities. Multivariate analysis combined these cytogenetic subgroups with percentage of BM blasts and number of cytopenias to generate a prognostic model. Weighting these variables by their statistical power separated patients into distinctive subgroups of risk for 25% of patients to undergo evolution to acute myeloid leukemia, with: low (31% of patients), 9.4 years; intermediate-1 (INT-1; 39%), 3.3 years; INT-2 (22%), 1.1 years; and high (8%), 0.2 year. These features also separated patients into similar distinctive risk groups for median survival: low, 5.7 years; INT-1, 3.5 years; INT-2, 1.2 years; and high, 0.4 year. Stratification for age further improved analysis of survival. Compared with prior risk-based classifications, this International Prognostic Scoring System provides an improved method for evaluating prognosis in MDS. This classification system should prove useful for more precise design and analysis of therapeutic trials in this disease.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.

Mixed myelodysplastic and myeloproliferative syndromes

Aplastic anemia, myelodysplastic syndromes (MDS) and chronic myeloproliferative diseases (MPD) are stem cell disorders. There is no clear-cut demarcation of them. Hypoplastic MDS displays features of aplastic anemia and MDS, on the other side mixed myelodysplastic and myeloproliferative syndromes (MDS-MPS) develop. In our collection of 566 MDS patients, features of myelodysplasia as well as myeloproliferation, MDS-MPS, were present in 25 patients (4.4%). Twelve patients had at the time of diagnosis megakaryocytic proliferation and thrombocythemia beside signs of MDS, and seven had myelodysplasia with granulocytic proliferation and leukocytosis. In another six patients, MDS was the first diagnosis and the proliferative phase developed later during the course of the disease. These patients can be characterized as MDS-MPS in evolution. All subjects had a variable degree of anemia. While the level of thrombocythemia has been relatively stable, the number of leukocytes has been progressive, but rarely extended beyond 100 x 10(9)/l. Ring-sideroblasts and myelofibrosis were frequent findings. Two more homogeneous MDS-MPS groups emerged in our analysis: sideroblastic anemia with thrombocythemia and a group fulfilling the criteria of Philadelphia chromosome negative and bcr-abl negative "atypical chronic myeloid leukemia (aCML)'. One patient with thrombocythemia and three with leukocytosis (23%) transformed to acute myeloid leukemia (AML). Men prevailed (12/13) in patients with leukocytosis and MDS-MPS in evolution. Of the 46% MDS-MPS patients with chromosomal aberrations, del(20)(q) is of interest.

Deletion of chromosome 20q associated with hypereosinophilic syndrome. A report of two cases

Deletion of the long arm of chromosome 20--del(20q)--is commonly associated with myeloid malignancies, in particular with myeloproliferative disorders (MPD), myelodysplastic syndrome (MDS), and acute myelogenous leukemia (AML). Its association with the hypereosinophilic syndrome (HES) had never been reported. In the present study we describe two patients with long-standing hypereosinophilia and features of atypical MPD or MDS carrying a del(20q) as a constant and isolated chromosomal abnormality. One patient, with an aggressive clinical course, died within 2 years, despite several lines of treatment. The other patient had a more indolent course consistent with that of an atypical MDS with eosinophilia.

dic(9;20): a new recurrent chromosome abnormality in adult acute lymphoblastic leukemia

Loss of chromosome 20 and rearrangement of the short arm of chromosome 9 were identified by banding analysis of three adult patients with acute lymphoblastic leukemia (ALL). The G-banding pattern suggested an identical deletion of 9p, but, also, an unbalanced translocation with chromosome 20 was taken into consideration. Dual-color chromosome painting with probes for chromosomes 9 and 20 revealed the presence of material from chromosome 20 at the short arm of the abnormal chromosome 9 in all three cases. Centromeric alpha-satellite DNA of both chromosome 9 and chromosome 20 was demonstrated by fluorescence in situ hybridization and indicated the presence of a dicentric chromosome. The hybridization of a YAC clone of the short arm of chromosome 20 proved that the dicentric chromosome contained the short arm of chromosome 20, which had been suspected from the G-banding pattern. Thus, the rearrangement was interpreted as dic(9;20)(p11;q11.?1). Because this was the sole chromosome abnormality in two patients, dic(9;20) may be a primary chromosome aberration in ALL. In one case, a 9q+ chromosome derived from a Philadelphia (Ph) translocation was involved in the formation of the dicentric chromosome. Immunophenotyping revealed CD10+ B-cell precursor ALL in all three cases. Whereas the two patients in whom dic(9;20) was the sole cytogenetically detectable change are in continuous complete remission for 10 and 45 months, respectively, the Ph+ patient relapsed with leukemia and died 8 months after diagnosis.

Characterization of 20q deletions in patients with myeloproliferative disorders or myelodysplastic syndromes

Deletions of the long arm of chromosome 20 are associated with several myeloid malignancies. We have analyzed the structure of the del(20q) in 30 patients and two cell lines. Twenty-one of the patients presented with a myeloproliferative disorder and nine with a myelodysplastic syndrome. Two categories of deletions were identified. Eighteen patients had a large deletion with loss of both G(+) bands from the long arm of chromosome 20. Twelve patients had small deletions with loss of one G(+) band from the long arm of chromosome 20. A chromosome paint was generated from a del 20q marker carrying a small deletion. This probe was hybridized to normal metaphases (reverse chromosome painting) and also to metaphases from patients with a del 20q (comparative reverse chromosome painting). All six small deletions analyzed were characterized by loss of the proximal G(+) band (q12) and retention of the distal G(+) band (q13.2). These data define a minimal deleted region extending from 20q11.2-20q13.1.